Abstract
Purpose: :
Caspase-14 is a member of cysteinyl aspartate specific proteinases, which are mainly involved in inflammation and apoptosis. Unlike other caspases, caspase-14 is not involved in the apoptotic caspase cascade, but is associated with differentiation of normal human epidermal keratinocytes and barrier formation. It is expressed and activated mainly in the epidermis and in tissues involved in barrier function such as choroid plexus, hair follicles and retinal pigment epithelium (RPE). The function of caspase14 in tissues other than skin is relatively unexplored. The purpose of this study was to characterize the expression of caspase-14 in retina under normal condition and during diabetic retinopathy (DR).
Methods: :
Experimental diabetes was induced in mice by intraperitoneal injection of streptozotocin (55mg.kg). Western blotting analysis was used to evaluate the expression of caspase-14 in postmortem human retina with or without DR and in mouse retinal cells; pericytes, endothelial cells (REC), RPE and astrocytes) isolated from C57BL/6J immortal mice. Immunofluroscence and immunohistochemistry were used to characterize the expression of caspase-14 in human and mouse retinal sections using specific caspase-14 antibody and the vascular marker Isolectin-B4.
Results: :
Caspase-14 is expressed in cultured RPE, REC and astrocytes. Diabetes increased the level of caspase-14 in mouse and human retina. Moreover, cleaved caspase-14 was highly expressed in human retina with DR. Immunolocalization demonstrated increased caspase-14 immunoreactivity in retinal vasculature and astrocytes during DR.
Conclusions: :
Caspase-14 is expressed in retinal cells involved in barrier function and activated during DR suggesting that caspase-14 may play a role in retinal vascular homeostasis. Further investigations are needed to explore the function of caspase-14 in retina.
Keywords: diabetic retinopathy • retinal pigment epithelium • retinal neovascularization